[RegCNET] Inquiry about HadGEM2 global datasets on public repository

[Graziano Giuliani]

On 11/06/2013 04:42 PM, Alexander Bryan wrote:
[...]
> Could someone explain the difference between the new and old data files and how
> those differences might affect my simulations?
[...]

We are short in disk space, so we changed the format from the original netCDF3 
to compressed netCDF4:

nccopy -k 4 -s -d9 file.nc3 file.nc4

This also lowers the network traffic on our side :) . In terms of information, 
no change. In terms of direct usage, requires netCDF V4.X library to read, but 
it is tranparent on the API level (no change in model code). Small overhead in 
CPU time to decompress after read, small gain in I/O time for reading less data 
from disk usually compensate or you can even have a small net gain in execution 
time. The overhead was just in the one time conversion 3->4.
IF anyway you REQUIRE netCDF3, make a box with netCDF4 binaries and get back to 
the classic format with

nccopy -k 1 file.nc4 file.nc3

G.

-- 
Graziano Giuliani - Earth System Physics Section
The Abdus Salam International Centre for Theoretical Physics
Strada Costiera, 11 - I - 34151 Trieste Italy